A revolutionary fortification (9)
I believe the answer is:
barricade
'fortification' is the definition.
(thesaurus)
'a revolutionary' is the wordplay.
I cannot quite understand how this works, but
'a' is found in the answer.
'revolutionary' could be 'cade' (I've seen this in other clues) and 'cade' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for barricade that I've seen before include "Improvised obstruction" , "Improvised fence" , "Temporary obstruction" , "Fortification, barrier" , "Barrier, to block a street perhaps" .)